Generator Setup with 400 amp service

Status
Not open for further replies.
G

Greg1707

Senior Member
Location
Alexandria, VA
Occupation
Business owner Electrical contractor
I am working at a house that has an unusual setup for the generator.

The house has a 400 amp service. Two 200 amp panels side by side in the basement.

It appears a generator was added at a later date. The generator supplies a 100 amp panel next to the two existing panels.

All of the circuits in panel #2 were moved to the other panels.

The 100 amp generator panel is also a sub panel of panel #1.

Kim1.jpgKim2.jpgKim3.jpgThere is a lock on the two 100 amp breakers to allow only one breaker to be ON.

I don't understand this setup?
 
Weird that they have both an ATS and a manual TS. :unsure:

I'm guessing they abandoned the 200a main (in the smaller exterior enclosure) and effectively have only a 200a service now.
 
I looks like the smaller panel is the emergency panel. I'm guessing that when it was installed, the breakers in panels 1 and 2 were rearranged so that panel 1 has the non-emergency breakers and the 100 amp panel has the emergency breakers. They didn't need panel 2.

When the generator is on, only the breakers in the emergency panel will be energized. The two 100 amp breakers in there are the incoming power. One is the generator. The other is the utility power (being fed from panel 1). The interlock keeps them from being on simultaneously.
 
LarryFine said:
Or:

The larger panel is on the ATS and the smaller panel must be manually transferred.
Click to expand...

Actually you are close. Mystery solved. The small panel was installed as a generator panel with a manual transfer switch in the panel. Later, a larger generator with an automatic transfer switch was installed and supplies panel #1. When the generator starts up the homeowner would need to turn off the sub panel to reduce the load.
 
Greg1707 said:
Actually you are close. Mystery solved. The small panel was installed as a generator panel with a manual transfer switch in the panel. Later, a larger generator with an automatic transfer switch was installed and supplies panel #1. When the generator starts up the homeowner would need to turn off the sub panel to reduce the load.
Click to expand...
Which would be a violation of 702.4
 
Status
Not open for further replies.
Top